Poly(N‐isopropylacrylamide) Interfaces with Dissimilar Thermo‐responsive Behavior for Controlling Ion Permeation and Immobilization

Abstract Stimuli‐responsive polymer interfaces with tethered poly( N ‐isopropylacrylamide) (PNIPAm) chains and its cross‐linked porous hydrogel as sensitive phases were fabricated by cycling an electronic potential in aqueous solution. Surface morphological analysis and electrochemical measurements revealed that, owing to their different novel structures, the PNIPAm chain‐modified interface showed ON/OFF switch behavior, whereas the PNIPAm gel‐modified interface exhibited a ‘breathing in' process. The results suggest that the interfacial physicochemical properties, which are greatly affected by the graft conformations and topologies of PNIPAm on the substrates, could be effectively modulated by easily varying the synthesis conditions and are investigated by simple electrochemical methods. The results also demonstrate that the ON/OFF switch behavior of the PNIPAm chain‐modified interface has potential applications in controlled ion/molecule permeation, and the ‘breathing in' mechanism of the gel‐modified interface might be applied to immobilize ions or nanoparticles. These thermo‐sensitive interfaces might be used to design adaptive/responsive biocompatible surfaces in a variety of areas.